Forage & Grass
31st March 2020

Widening the gap in heading dates pays off

LG Monarch Intensive Grazing Grass Mixture

There’s nothing ‘usual’ or typically’ when it comes to grass growth and cutting dates in some parts of the country if the past few years are anything to go by. We’re seeing more volatility in weather patterns and we’re warned that this is a sign of things to come.

There’s nothing ‘usual’ or typically’ when it comes to grass growth and cutting dates in some parts of the country if the past few years are anything to go by. We’re seeing more volatility in weather patterns and we’re warned that this is a sign of things to come. So, say two leading grassland specialists, we need to cater for in our choice of grass seed mixtures.

Opting for mixtures that offer more flexibility can be very wise, when it comes to cutting dates. “The typical silage mixtures with bountiful yields of high quality grass are there, but only for a short window,” says Limagrain’s grass seed manager Ian Misselbrook.  “If this is missed, quality and yield fall away rapidly.”

“Most dairy units look for two cuts of silage and some grazing from a grass silage ley,” he says, adding that, despite the ‘noise’ multicut systems are still a minority practice and not one that suits all farms, when accessibility of fields and soil type are considered.

“The aim is usually a good first cut then a second cut six weeks later,” he adds.

“But if we look at the past couple of years, this cutting pattern has been a challenge. Last year, 2019, grass didn’t follow its normal pattern of a peak, then a dip mid summer and then regrowth. It just kept growing at pretty much the same rate.”

Then the 2018 season was being equally erratic with a cold spring, late start to growth and then exceptionally dry conditions. “If farmers didn’t get a top class first cut they were struggling.”

And although there was plenty of grass growth last year, harvesting wasn’t without its problems. ‘Grass grew so vigorously, that a lot of second cut was ready for cutting after only four weeks, but, for routine reasons and contractor availability, it was cut after six weeks by which time its quality had really dropped off. Producers have seen the consequences this winter when this forage hasn’t produced the milk yields they’d anticipated.”

Longer cutting window – less pressure
Mr Misselbrook suggests that growing grass seed mixtures with a wider heading date will add some flexibility and take the pressure off.

“Typical silage mixtures used on UK farms will have a window for cutting of about four days. These mixtures are predominantly intermediate perennial ryegrasses that head in the same narrow window of just a few days.’

They are designed for high yields of good feed quality, to be cut at a D value over 70 and high dry matter. “And they do exactly what it says ‘on the tin’, but catching this ideal time is limited and challenging if conditions are not ideal.”

“On an ideal site, in an ideal season, intermediate perennial ryegrass mixtures will head at the same time and provide prize winning silage with an ME of 12 or above, but we hardly ever get these near perfect conditions,” says Mr Misselbrook. “Once these heading dates have passed, quality falls off rapidly across the whole crop as all the plants are at the same vegetative stage and move into the reproductive stage.”

Instead, he suggests that farmers look at mixtures with a wider heading date. “These will have more varieties of grasses and include intermediate sand late perennial ryegrasses, offering a range in heading dates and a 12- or 14-day window for harvesting.”

He adds that if these mixtures are harvested in the first half of the window, while the later perennial ryegrasses may not have headed, they will still be in their vegetative leafy stage and offer high feed value. If cutting date is later, while the intermediate grasses may be past their best, the late perennial ryegrasses will be in their prime.

“It’s also worth including some tetraploid ryegrasses in the mixture too, as they are recognised for their higher nutritive value. They’re proven to have better balance of sugars and digestible fibre (DNDF) which is key in maximising the feed value of the silage.”

Seed merchants will include heading dates of grass seed mixtures in their literature to help farmers in their selections. “Look for any accreditations too that indicate high yields and feed value,” he says. “We include the LGAN accreditation on some Limagrain grass seed mixtures; most of these have diploid and tetraploid ryegrasses, and intermediate and late varieties depending on their requirements.

“Being a bit more discerning will help farmers accommodate and adapt to the changing weather patterns.”

Across in Ireland, Paul Flannagan from DLF Ireland is also talking to his farmer customers about more ‘fail safe’ mixtures.

“I know that traditionally we’ve opted for silage mixtures made up mainly of intermediate perennial ryegrasses. These can give top yields of high feed value grass. But that’s only where conditions are especially favourable,” he says.

He estimates that in 60% of cases, conditions are not ideal and as a result yield and quality suffer. “Either it rains, or the contractor is delayed, or there’s a break-down,” he adds. “The trouble is, with these mixtures you only have a four- or five-day window to cut the crop at its best. After that quality falls dramatically.”

Instead, to spread the risk, DLF Ireland is seeing farmers opting for mixtures with wider heading dates, giving a window for harvesting of 15 or 16 days. “These crops will hold their quality and give farmers an extra 10 days or so to harvest the crop.”

He admits that while those bumper yields might not be there, the overall lifetime productivity of these mixtures with wider heading dates is probably a lot higher. Instead of a crop achieving its potential one in every three years, you’re getting good crops far more consistently and at least two out of three years – that’s a lot of extra productivity from a grass ley if we consider lifetime yield.”

And he says farmers are realising this, judging by their increased interest in some of the wider heading mixtures. “Take Sinclair McGill’s Scotsward. This mixture heads a bit later and it has a mix of intermediate and late perennial ryegrass so the window of opportunity for cutting – without any real loss in yield or quality – is about 14 days.

“Farmers find that digestibility and energy levels in the silage are less variable one year to another and while yields might not be those that the top performing silage mixtures achieve in a perfect year, the added reliability across the lifetime of the ley more than compensates.”

Mr Misselbrook admits that farmers need to review the last few seasons and decide what sort of mixture suits them best. “And be honest, don’t look at one season in isolation, but across say a five-year period and consider whether the top yielding silage mixtures are coming up with the goods on your farm, or whether you should build in a bit more flexibility and take a bit of the risk out of the grass crop.”

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